This invention relates to a stalling prevention apparatus for preventing an engine from stalling at starting of a vehicle, which is particularly used to good advantage in a vehicle equipped with a manual transmission.
In passenger cars and the like equipped with a small-displacement engine with a manual transmission, with a small output torque at the low-speed range compared to trucks, the engine tends to cause stalling unless the driver carefully sets the degree of pressing down the acceleration pedal and the clutch connection timing at starting of the vehicle.
Such an engine stalling at starting of the vehicle can be prevented by skill of the driver to some extent.
In general, stalling of the engine at the start of the vehicle is caused, in addition to a small output torque of the engine at its low rotation speed range, by a delay in response of the air intake system from pressing of the acceleration pedal until the engine output torque increases. Specifically, since a length of time is required after the acceleration pedal is pressed down to open the throttle valve until a large amount of fuel mixture reaches the engine, if the clutch is actuated simultaneously with pressure of the acceleration pedal, stalling tends to occur due to an insufficient increase in output torque of the engine.
For a vehicle equipped with a manual transmission in which the driver starts the vehicle while adjusting the pressing down of the acceleration pedal and the clutch pedal, some skill is required to start the vehicle. Therefore, a beginner who is not experienced in starting the vehicle tends to cause frequent stalling of the engine.
On the other hand, for a vehicle equipped with an automatic transmission with a torque converter, in which the output torque in the low rotation speed range of the engine is enhanced, generation of stalling at starting of the vehicle is reduced, and even a beginner can easily start the vehicle. However, the use of a torque converter inevitably results in increases in costs of the power transmission system and weight of the vehicle. Especially, it has been a problem to use a torque converter in a small-displacement vehicle which has much limitations in the engine room space and the like.